Figure 1

(a) Part of the energy spectrum of $\alpha$ decays correlated with the ER implantation within the time interval of $\Delta T(\mathrm{ER}–{\alpha }_1)⩽200$ ms. The data were collected during the “beam off ” interval. $\alpha$-decay energies are given in keV. (b) The $\alpha$-$\alpha$ correlation plot for the ${\alpha }_1$ decays from (a), measured within the time interval of $\Delta T(\alpha –\alpha )⩽2$ s. (c) Projection from (b) on the $E_{\alpha 1}$ axis. (d) $E_{{\alpha }_1}–E_{\gamma }$ spectrum for ${\alpha }_1$ decays from (b) in coincidence with $\gamma$ rays within 5 $\mu$s. The inset shows the spectrum of $\alpha$ decays observed in coincidence with the 77.2 keV $\gamma$ decays without any further conditions, except for the coincidence time interval of 5 $\mu$s. (e) The result of the GEANT Monte Carlo simulation for the 7016-keV decay (see text for details).Reuse & Permissions

Figure 2

Decay scheme of ${}^{181}\mathrm{Pb}$ and ${}^{177}\mathrm{Hg}$ deduced in our work (see text for details). Shown are $\alpha$-decay energies $E_{\alpha }$, relative intensities $I_{\alpha }$, reduced $\alpha$ widths ${\delta }_{\alpha }^2$, and hindrance factors ${\mathrm{HF}}_{\alpha }$. The tentative 7093(15)-keV $\alpha$ decay is shown by a dashed line. The $1.50–\mu \mathrm{s}\hspace{0.5em}{I}^{\pi }=13/2^{+}$ state at 323 keV in ${}^{177}\mathrm{Hg}$, identified in an in-beam study [6], is shown for completeness. The reduced $\alpha$ widths were calculated with the Rasmussen prescription [28] by assuming $\Delta L=0$ decays. The ${\mathrm{HF}}_{\alpha }$ value for the 7093-keV decay was calculated relative to the 7016-keV decay, for which ${\mathrm{HF}}_{\alpha }=1$ was assumed. All spin-parity assignments are tentative and are shown in parentheses.Reuse & Permissions